Image view which supports image drag and drop.

XSDragImageView.m

#import <Foundation/Foundation.h>

@interface XSDragImageView : NSImageView <NSDraggingSource, NSDraggingDestination>
{
	BOOL isHighLighted; // 테두리 표시 여부를 나타내는 값 
}
@end

@implementation XSDragImageView

#pragma mark - init and dealloc

-(id)initWithFrame:(CGRect)frame 
{
	self = [super initWithFrame:frame];
	if(self) {
		[self registerForDraggedTypes:@[NSPasteboardTypeTIFF, NSPasteboardTypePNG, NSFilenamesPboardType]];
	}
	return self;
}

-(id)initWithCoder:(NSCoder *)aDecoder
{
	self = [super initWithCoder:aDecoder];
	if(self) {
		[self registerForDraggedTypes:@[NSPasteboardTypeTIFF, NSPasteboardTypePNG, NSFilenamesPboardType]];
	}
	return self;
}

#pragma mark - Mouse Action

-(void)mouseDown:(NSEvent *)theEvent
{
	NSDraggingItem *dragItem = [[NSDraggingItem alloc] initWithPasteboardWriter:self.image];
	[dragItem setDraggingFrame:self.bounds contents:self.image];
	[self beginDraggingSessionWithItems:dragItem event:theEvent source:self];
}

#pragma mark - Source Operation

-(NSDragOperation)draggingSession:(NSDraggingSession *)session sourceOperationMaskForDraggingContext:(NSDraggingContext)context 
{
	return NSDragOperationCopy;

	// switch(context) {
	// 	case NSDraggingContextOutsideApplication:
	// 		return NSDragOperationCopy;
	// 		break;
	// 	case NSDraggingContextWithinApplication:
	// 	default:
	// 		return NSDragOperationGeneric;
	// 		break;
	// }
}

#pragma mark - Destination Operation

-(NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender
{
	NSPasteboard *pboard = [sender draggingPasteboard];
	NSString *availableType = [pboard availableTypeFromArray:[self registeredDraggedTypes]];
	if(availableType) {
		isHighLighted = YES;
		[self setNeedDisplay:YES];
		return NSDragOperationCopy;
	}
	return NSDragOperationNone;
}

-(NSDragOperation)draggingEntered:(id <NSDraggingInfo>)sender
{
	NSPasteboard *pboard = [sender draggingPasteboard];
	if([NSImage canInitWithPasteboard:pboard]) {
		NSImage *copiedImage = [[NSimage alloc] initWithPasteboard:pboard];
		self.image = [copiedImage autorelease];
		return YES;
	}
	return NO;
}

-(void)concludeDragOperation:(id <NSDraggingInfo>)sender
{
	isHighLighted = NO;
	[self setNeedDisplay:YES];
}

@end